Mainframe, Performance, Topics Podcast

Episode 36 "Telum Like It Is"

EPISODE 36 "TELUM LIKE IT IS" WHAT’S NEW * z/OS dependencies moved from Semeru 17 to 21 [https://www.marnasmusings.com/2025/03/keeping-up-with-javas.html]. EOS for Semeru 11 is 30 Nov 2025. * Manual of the Moment: z/OS 3.1 Planning for Installation refresh, Software Dependencies section [https://www.ibm.com/docs/en/zos/3.1.0?topic=installation-software-requirements-running-zos-31] MAINFRAME - POSITION Z/OS FOR IBM Z17 * z/OS V2.4 and higher is supported on IBM z17. Use SMP/E FIXCATs to find the necessary service. * z/OS Sysplex requirements for coexistence is z15, z16, and z17. * Exploitation for z17 in z/OS includes: Workload level sustainability and power consumption, Workfload classification pricing, new CL6 link technology, BCPii and HMC hardened security, CF Level 26, and more. MAINFRAME ALSO - PREVIEW OF Z/OS 3.2 [https://www.ibm.com/docs/announcements/AD25-0004] * z/OS 3.2 will IPL on z15 and higher servers. Planned GA is 3Q2025. * Some new functions previewed, but stay tuned for further announcements with more complete functions. * Highlights: new REST APIs for doing installation of service updates, support for direct encryption to tape, new z/OSMF Storage Management interface, RACF certificate support for multiple altnames, and more. PERFORMANCE - IBM Z17 HIGHLIGHTS * Telum 2 processor has the 2nd generation on-chip AI accelerator, with 8-bit integer (INT8) and 16-bit floating point (FP16) datatypes for more thruput. * 5nm (from 7nm), with clock speeed of 5.5 GHz (from 5.2). * DPU has 4 port cards (from 2), with energy consumption reduction. DPU accessible from other chips and DCMs. * 1 to 4 processor drawers. 4-drawer models are Max183 and Max 208. * Memory 64 TB (from 40). * Measurements with new Channel Measurement Groups 4 and 5, with SMF 73 support. TOPICS * Martin and Marna discuss how they prepared materials for IBM z17, with the Upgrade Workflow and Redbooks. ON THE BLOG * Marna's blog [https://www.marnasmusings.com/] * Martin's blogs [https://mainframeperformancetopics.com/] SO IT GOES

Episode 35 "In search of EXCELence?"

What’s New * z/OS dependencies moved from Semeru 11 to 17 [https://www.ibm.com/docs/en/zos/3.1.0?topic=installation-software-requirements-running-zos-31] before November 2025 * Manual of the Moment: MVS Extended Addressability Guide [https://www.ibm.com/docs/en/zos/3.1.0?topic=mvs-zos-programming-extended-addressability-guide] for learning about address spaces, data spaces, and hiperspaces. Mainframe - Looking at ages of fixes you haven't installed yet * IBM has started adding a REWORK date to PTFs. The date may be a day or two before the actual availability date. * Use case example: requirement with a policy that Security/Integrity (SECINT) PTFs that meet some criteria must be installed within xx days of availability. * Fits nicely with the z/OS UUID support, from Episode 34 [https://podcasters.spotify.com/pod/show/marna-walle/episodes/Episode-34-Homeward-Bound-e2cmmv2]. Performance - Drawers, Of Course * Martin explores the IBM z16 drawers, frames, and cache hierarchy. * All of an LPAR’s logical processors and memory should be in the same drawer. * Important because cross-drawer memory and cache accesses are expensive. Topics - Excel Love It Or Hate It * Martin and Marna discuss how they use Excel, and what they like and dislike about it. * Graphing and customization difficulties were investigated. On the blog * Marna's blog [https://www.marnasmusings.com/] * Martin's blogs [https://mainframeperformancetopics.com/] So It Goes...

Episode 34 "Homeward Bound"

EPISODE 34 "HOMEWARD BOUND" MAINFRAME - Z/OSMF SOFTWARE MANAGEMENT UUID [https://www.ibm.com/docs/en/zos/3.1.0?topic=services-retrieve-zos-system-uuid] * What it is: ability to programmatically retrieve a unique value (UUID) which can then be used to find out installation information about the active z/OS system. This function is optional. * Requires: z/OS 3.1, an SMP/E CSI specific to that software instance, and an installed usermod which is provided by z/OSMF Software Management. * How it works: once the UUID has been encoded into your z/OS system's LPALIB data set, you can use a REST API to retrieve the UUID. Then, this allows you to use the UUID to run many other REST APIs to look at the installed software with assurance that you are looking at the actively running system software instance. You must ensure that for each new software instance, you install a new UUID. The UUID is also available from the D IPLINFO [https://www.ibm.com/docs/en/zos/3.1.0?topic=command-displaying-ipl-information-iplinfo] command. PERFORMANCE - LOGICAL PROCESSOR HOME ADDRESSES * This is the LPAR's preferred physical location for a specific logical process to be dispatched. Drawer, DCM, chip, core. Degrees of meaning for Verical High, Medium, Low, and Dedicated. * z16 support is in the SMF 70-1 records, OA62064 [https://www.ibm.com/support/pages/apar/OA62064] . Better than SMF 99-14 in some ways. * Useful for an analysis of effect of PR/SM weights and HiperDispatch, verify location of ICF and IFL LPARs. * Logical processor is not always dispatched to its home address. VH and Dedicated will always dispatch to the home processor. Location of memory is not included, although SMF 113 gives hints. * Might need SMF 99-14 in addition, as it has affinity nodes, which 70-1 doesn't. * All in all, a very useful advancement in the instrumentation. TOPICS - USEFUL TIPS FOR DEBUGGING A DFSORT E15 EXIT * Martin explores his experiences with DFSORT E15 and offers advice. * DFSORT E15 is great at flattening records and enhancing filtering. You might find yourself needing to maintain this exit, which others have written. * Some useful advice is: let the exits do the I/O for you, do a COPY first, stop after one record at first, write diagnostic data into output records, forcing an abend can help, code a SYSUDUMP DD, maintain a DFSORT symbols convention, GETMAIN your working storage, and you can write to the spool. ON THE BLOG * Marna's blog [https://www.marnasmusings.com/] * Martin's blogs [https://mainframeperformancetopics.com/] SO IT GOES

Episode 33 "These Boots Were Made"

Episode 33 "These Boots Were Made" What’s New * Preliminary z/OS 3.1 Upgrade materials [https://www.ibm.com/support/pages/apar/OA63269] * Python 3.1.1 zIIP enablemment OA63406 [https://www.ibm.com/support/pages/apar/OA63406] and PH52983 [https://www.ibm.com/support/pages/apar/PH52983] Mainframe - * Requires: z/OS V2.5 with PTFs, IBM z16 with microcode. Has both driving and target system requirements, use IBM.Function.ValidatedBoot FIXCAT. * Front end: Siging the in-scope artifacts (NUCLEUS, LPA, IPL Text, and SA Dump Text), z16 is not required here although z/OS V2.5 and PTFs are. * Back end: Verification of those signed in-scope artifacts. z16 with correct microcode level is required here (with z/OS V2.5 and PTFs). * Security set up work is required. Performance - Open Data Sets, Part 2 * Follow on, from Part 1 which was physical open and close of data sets as seen by z/OS. * This is about Db2 with the notion of logically Open and Closed data sets. * Its main role is to manage inter-Db2 read/write interest, for Datasharing efficiency purposes. * Two Db2 subsystem parameters have traditionally been used to control pseudoclose: PCLOSET and PCLOSEN. PCLOSEN is gone in V12 with APAR PH28280 [https://www.ibm.com/support/pages/apar/PH28280], as part of a DSNZPARM simplification effort. So PCLOSET would need adjusting down to whatever mimics PCLOSEN - in anticipation of this APAR or V13. Topics - Messing With Digital Electronics * Martin explores his experiences with input devices (Stream Decks, Quick Keys, ...) * Martin has even built his own input devices: having an RFID card kick off automation, rotary encoders, USB Human Interface Device. On the blog * Marna's blog [https://www.marnasmusings.com/] * Martin's blogs [https://mainframeperformancetopics.com/] So It Goes

Episode 32 "Scott Free"

EPISODE 32 "SCOTT FREE" WHAT’S NEW * Preview of z/OS 3.1 [https://www.ibm.com/common/ssi/ShowDoc.wss?docURL=/common/ssi/rep_ca/3/897/ENUS223-013/index.html] MAINFRAME - SMFLIMXX PARMLIB MEMBER [https://www.ibm.com/docs/en/zos/2.5.0?topic=sys1parmlib-smflimxx-specifying-region-memlimit-values] * IEFUSI exit replacement with a parmlib member, related to storage and limits that can be specified. * Functions are delivered as continuous delivery, such as the SAF check filter, and number of shared pages used. * In z/OS 3.1: Dedicated Real Memory Pools to assign memory to a specific application, like zCX, in all frame sizes. PERFORMANCE - OPEN DATA SETS, PART 1 * Looking at many open data sets (100s of thousands) for middleware. * ALLOCxx's SWBSTORAGE [https://www.ibm.com/docs/en/zos/2.5.0?topic=defaults-statements-parameters-allocxx] has to specify ATB to put control blocks above the bar. Applications need to exploit the service. * Monitoring virtual storage is key here, and remains important. The number of volumes needed affects how much memory is needed, so there is no one answer. TOPICS - EVOLUTION OF A GRAPH * Martin explores the large improvements he's made with his custom graphing programs. * Start with naive rows and columns, with rigid labels. * Then, generating the titles with REXX. Then, using REXX to drive GDDM directly. Then, use REXX to generate many more data point and plotting them directly. Then, have REXX generate the series names. * Martin encourages all to evolve their graphs, to tell the story better, and run more efficiently. CUSTOMER REQUIREMENT * ZOSI-2195 "Extended GDG causes space issues", has been satisfied. IGGCATxx's GDGLIMITMAX [https://www.ibm.com/docs/en/zos/2.5.0?topic=configuration-statements-parameters-iggcatxx] with OA62222 on V2.3. ON THE BLOG * Marna's NEW blog location is here [https://www.marnasmusings.com/] * Martin has quite a few new blog articles here [https://mainframeperformancetopics.com/] SO IT GOES